The Constitution of India divides the powers between the Union and the State governments through three lists :
1. UNION LIST - It contains subjects of national importance about which a uniform policy is needed throughout the country. Only the Union Government can make laws on these. Examples : defence, foreign affairs, banking, communications and currency. (Presently 97 subjects.)
2. STATE LIST - It contains subjects of state and local importance. Normally only the State Governments can make laws on these. Examples : police, trade, commerce, agriculture and irrigation. (Presently 66 subjects.)
3. CONCURRENT LIST - It contains subjects of common interest to both the Union and the State Governments. Both can make laws on these; but if their laws conflict, the law made by the Union Government prevails. Examples : education, forest, trade unions, marriage, adoption and succession. (Presently 47 subjects.)
4. RESIDUARY SUBJECTS - Subjects that do not fall in any of the three lists, such as computer software, are called residuary subjects, and the Union Government has the power to legislate on them.